Other mistake: The clocks as we learn later in the film stop at 03:07 due to that being the time the witch died. However, the grandfather clock we see for the first time has stopped at 03:07. We then see it stop at 03:07 the next night too. However the minute hand is in a different spot to when it first stopped - it should have stopped at precisely the same point.
Trivia: The "Annabelle" doll seen in the opening sequence of the film was actually a regular "Raggedy Ann" doll in the real-life story that inspired the scene. The doll was redesigned to its current, much more grotesque form for several reasons: First, to make it more cinematic. And second, to avoid legal troubles with the copyright holders on Raggedy Ann. The filmmakers and Lorraine Warren also stated that they were interested in re-designing the Annabelle doll because they were afraid if they used a real Raggedy Ann doll, it would frighten children who might own them.